1. Field of the Invention
This invention relates generally to communication systems and, more particularly, to systems having digital radio transmitters and receivers. When both the radio transmitter and receiver are programmable, the communication systems become much more flexible.
2. Background of the Invention
With the movement of radio broadcast technology toward digital implementation, present efforts are directed to providing consumers with low-cost, high performance receivers that are able to decode the complex digital signals that will be broadcast by the radio stations. Transmitters are burdened with the task of conveying information to the receivers. Once designed and in operation, the transmitters become a static object whose sole function is to convey the digital media to the radio receivers. Because the radio receiver technology has to be designed to be compatible with the radio transmitter, a severe constraint is placed on the receiver design when an upgrade of the entire system is attempted.
Thus, the design of a radio receiver is strongly linked to the architecture of the transmitter because a common coding and modulation scheme is required by both system components. Currently, because of cost and power considerations, a custom ASIC (Application Specific Integrated Circuit) component is frequently used to implement demodulation and decoding algorithms. The ASIC component has all of the limitations inherent in a hardwired component, such as lack of the ability to re-use in the event of even relatively minor changes to the circuit design.
However, data processing components in general have become much more affordable. The general purpose microprocessors (CPUs), the specialized digital signal processors (DSPs), and memory components have participated in the reduction in cost. Consequently, functionality of great complexity can now be considered for radio systems while remaining relatively affordable.
A need has therefore been felt for apparatus and an associated method having the feature that modifications can be made to a digital communication system without requiring changes in the apparatus implementation. It would be a further feature of the apparatus and associated method that the digital transmitter unit of the communication system can be changed by changes to the transmitter unit programming. It would be yet another feature of the apparatus and associated method that the receiver unit of the communication unit can be changed by changes to the receiver unit programming. It would be yet another feature of the apparatus and associated method that communication system upgrades can be performed by changes to the programming of the digital transmitter unit and/or the digital receiver unit. It would be a still further feature of the present invention that the updates to the receiver unit can be provided by the transmitted signal stream.